Valve mechanism for fluid-operated rock drills



July 10. 1928.

'. I. L.HOLMAN ET AL VALVE MECHANISM FOR FLUID OPERATED ROCK DRILLS Filed Jan. 20, 1927 ill) Patented July 10, 1928.

UNITED STATES PATENT OFFICE.

JOHN LEONARD HOLMAN AND ARTHUR TREVE HQLMAN. GF CAMBORNE. ENGLAND, ASSIGNORS TO HOLMAN BROTHERS LIMITED, 01? CAMBOBITE. ENGLAND, A. BRITISH COMPANY.

VALVE MECHANISM FOR FLUID-OPERATED ROCK DRILLS.

Application filed January 20, 1927, Serial No, 162.313. and in Great Britain October 14, 1926.

This invention consists in improvements in or relating to valve mcehanism for fluidoperated rock drills and like tools. The invention relates to that l ind of tool in which there is a cylinder. a reciprocating piston therein inlet ports for the driving fluid leading respectively to opposite ends the. cylinder and a valve for controlling the admission of driving fluid alternately to the ports aforesaid.

The type of valve to which the invention relates is a flap valve which may convenient ly be hinged at or near one end and operates by oscillatory movement about its hinge to control by its opposite 'laces respectively the two inlet ports which lead to the opposite ends oi the working cylinder. In this type of valve oscillatory movement is brought about by variations in the pressure acting on the opposite faces of the valve.

The principal object of this invention is to provide means whereby the movement of the flap valve from one position to the other is effected more rapidly and with greater certainty than in constructions hitherto proposed.

According to the present invention in a fluid-operated rock drill or like tool of the kind described having valve mechanism of the type specified in which a llap valve has one face closed against an inlet port by the pressure on its opposite face of the driving fluid entering the alve chamber, there is provided means to admit pressure fluid to the aforesaid face of the valve which is closed against its corresponding inlet port so as to balance or partially balance the pressure oF the driving fluid acting to hold the valve closed. \Vhen the pressure of the driving fluid is reduced by the exhaust to below that of said pressure fluid, the latter will act to move the valve to close the other of the two inlet passages.

A feature of the invention consists in a. valve having means to admit pressure fluid. as above described. to the face of the valve which is closed against its corresponding inlet port and which is arranged so that the length of the valve transverse to the axis about whi h it oscillates is parallel with tin" throughway axis of the cylinder the lluidadmission to which is controlled by the valve.

Conveniently. the aforesaid means to admit pressure fluid to the closing face of the valve is constituted by a throughway aperlure or apertures leading from one face of the valve to the other.

Preferably. one ftltt of the valve seats on to the outer wall of the cylinder or on to a liner surrounding said outer wall, and said valve face is recessed to form a cavity with which the aforesaid throughway apertures in the valve eonnnunicate.

In order that the invention may be more clearly understood one form thereof will now he described by way of example only with the aid of the accompanying drawings in which Figure. 1 is a. sectional elevation through a cylinder and valve of a rock drill, the section being taken in a plane containing the axis of the cylinder; and

Figure 2 is a plan of the valve.

Only so much of a rock drill as is necessary to the understanding of the invention has been illustrated. As is usual. there is provided a main cylinder in which is a hammowpiston ll associated in known manner with a twist-bar 12 and the usual ratchet twist mechanism. In the wall oi the cylinder is a free exhaust port 13. the opening and closing of which is controlled by movement of the piston 11.

\Vithin a valve chamber 14 there is a main air-inlet valve 15 which is in the form of a plate-valve hinged at one end 16, by means of a transverse rib which is received within a. eorre.pondingly shaped groove in a transverse inner portion of the valve-chamber. Compressed air enters the chamber 14 through a main inlet 17 opening into one end of the VtllVP-(llflfllbtl' in the region of the free end of the valve 15. A transverse bridge 18 serves as one seat for the valve 15 and air is enabled to pass between the adjacent faces of the bridge and the valve to a.

'inuin air-inlet port if) when the valve is in the lower position illustrateth The port it) i ii1l-l l! left halal end oi the eytimleiltl lll and another inlet port Qt) tor the right-hand end of the cylinder i mantrolled by the lower tat-e ot' the valve to.

The valve has a recess ttl lorlnid in its lower taco which seats onto the cylinder and apertures 4t thrmin'li the valve afford connnnniration between the air-inlet l7 and the said recess.

In operation compressed air enters the main inlet 1?. and. in the position of the valve illustrated. passes ver the valv through the port H) to the lett-l and end of the cylinder. and also through the iqjiortnrcs rl into the cavity lornicd hy the re ess A1 and the outer wall l' the cvl nder it). 'llncavit ll) presents a sin-face of such dimensions to the nn-sorroi the driving llnid adniittcd through the apcrtnrs it that the total pressure of the air in this cavity hill ancrs or Iatri-all halanr s the pressnie of the air on the upper urface of the alvc 15. As the piston travels to the i'ight it opens the exhaust port til. \vln-rrnpon tllt' itlE-v-%llll is innnta'liatctv reduced in the lel't-hand end of the cylinder and above the valv l5. ons'cqncntlv. the valve i.- llnn very rapidly raised. thcrch v closing the passage 19 hy engagement ol' the upper surface oi the valve to with the liridge l rv. (lac niainl v to the pressure of the llnid in the cavit al'm'csaid. 'l h'r movement of the valve is as .tiecl lll' the compression produced in the right-hand end oi the cylinder which acts on 2h. under snrtare oi the valve l? through the port it). The compressed air then flows from the. inlet. 17 through the port it) to the right-hand tare of the piston. As the piston travels to the left; it opens the exhaust port l3 whereupon the pressure. is reduced in the rigrhthand end of the cylinder and under the valve lfi. The pressure on the portion of the valve projecting beyond the bridge 18 into the inlet IT and the compre sion from the front. end of the cylinder on the part of the valve in the passage it) immediately closes the valve and the cycle of operations is reversed, and subsequently repeated.

The construction descrihcd above in detail is given as one example onlv of the invention, and it is to he understood that the design of the parts may be modified without departing from the scope of the invention as defined h the appended claims. The invention 1113). he appled to any valve nicrhanisin ot' the type described. for example to any of the tolistl'lhftions descrihed and ilinstrated in the specification of British application for Letters Patent No. 6307 of 1.926.

e claim:

1. For a fluid-operated rock-drill. the comhination ot' a valve-chamber having two ontlet-ports leading therefrom. a swinging flap- Valvo which is l'iingt-il at. one end in said chandler and which has two valv -tacos for controlling respectively the two mltletepor-ts and means which, when one valve-face i; held against one of said ports in pressur of drivingdluiel on its opposite lat-c. will admit drivincytlnid also to that valve-lace which is held against the outlet-port lint not that portion that. covers the port. so as rt least partially to lmlancc the-pressure ol' the driving llllltt acting on its. other face to hold the valve clued.

2. For a. fluid-operated rock-drill, the con'iliination of a valvc-chan1her having two outlet-port's leading tlaere't'ron'i. a swinging Hap-valve which is hinged at on end in said chamber and which has two valve-times for controlling respectively the two ontlet-ports and at least one tllIOHL'hWS V passage in. the valve which. when one valve-face is held against one of said ports by pressure of driving-fluid on its opposite Face. will admit: drivingflnid also to that valve-face which is held" against the outlet-port hut not that portion that covers the port so at least partially to halancc the pressure of the driving tlnid acting on its other face to hold the valve closed.

For a fluid-operated rock-drill, the con1- hination of a drill-cylinder. a valve-clnmiher situated in the side of the tlrill-c vlinder and having, two outlet-ports leading therefrom. a swinging flap-valve which is hinged at one end in said chainher and which has two valve-faces for controlling respectively the two outlet-ports and means which. when one valve-face is held against one ol said ports by pressure of driving-fluid. on its opposite face. will admit driving-fluid also to that valve-face which is held against the ontletport but not that portion that covers the port, so as at least partially to. balance the pressure of the driving-fluid acting on its other face to hold the valve closed.

4. For a fluid-operated rock-drill the coinhinatiion of a valve-chamber having two outlet-ports tending therefrom. a swinging flapvalve which is hinged at one end in said chamber and which has two valve-faces on opposite. sides of the valve for controlling respectively the two outlet-ports and means which. when one valve-face is held against the appropriate outlet-port by pressure of the driving-fluid on the opposite side of the valve. will admit driving-fluid between the side of the valve having that valve-face and an adjacent wall of the valve chamher so as at least partially to halance the pressure of the driving-fluid acting on the said opposite side of the valve.

5. For a. fluid-operated rock-drill the combination of a valve-chamber having two outlet-ports leading therefrom, a swinging flapvalve which is hinged at one end in said chamber and which has two valve-faces on opposite sides of the valve for controlling respectively the two ontlet ports. a. recess in one side of the valve, and means which. when Ill) the valve-face on that side of the valve is held against the a]'vpropriate outlet-port by pressure of the driving-fluid on the opposite side of the valve, will admit driving-fluid to said reress so as at least partially to hal anee the pressure of the driving-fluid acting on the said opposite side of the valve.

6. For a fluid-operated roeli-drill the coinhination of a valve-eh an [her having two outlet-port's leading therefrom. a swinging flapvalve whieh is hinged at one end in said ehalnher and \\'lll('ll has two val've-l"a"es on opposite sides of the valve [or controlling respeetively the two outlet-ports and at least one thronghwav aperture in the valve, whieh. when one valve-taee is held against the appropriate outlet-port hv pressure of the driving-fluid on the op )osite side of the valve, will admit driving-thud between the side of the valve having that valve l aee and adjacent wall of the valve-ehainlwr so as at least partially to halanre the pressure ot the driving-fluid aeting on the said opposite side ot the valve.

T. For a t'luid operated rook-drill, the rolnhination ot a valve-ehainher having two outlet-ports leading therel'roln. a. swinging flap-valve which is hinged at one end in said ehainher and which has two valve-'taees on opposite sides of the valve tor mull-oiling respectively the two outleteports. a recess in one side of the valve. and at least one throughway aperture in the valve which when the valve-face on that side ol" the valve is held against the appropriate outlet-port by pressure of the drivingtluid on the opposite side of the valve, will admit drivingflnid to said recess so as at least partially to balance the pressure of the driving-fluid acting on the said opposite side of the valve.

8. For a fluid-operated rock-drill tho eoinhination of a drillavylinder, a valverhainher situated on the side of the drillarylinder and having two ontlet ports leading therefrom, a swinging flap-valve Wlllt'l! is hinged at one end in said ehainher and whirh has two valve-faces on opposite sides ol' the valve tor controlling respectively, the two outlet-ports a recess in one side of the valve, and at least one throughwav aperture in the valve which when the valve-t'aee on that side of the valve is held against the appropriate outlet-port h v pressure of the driving-fluid on the opposite side ot' the valve, will admit driving tluid to said reeess so as at least partially to balanee the pressure of the driving-fluid arting on the said opposite side of the valve.

9. For a tluid-operz'ited rock-drill, the eomhination ot a eylinder having a valveehaniher. a short direet; outletpassage leadin; from the 'v'illVtdllt!llllIQ! to one end of the cylinder. :1 lu'ida e situated hetween two ends of the rhainher and atl'ordin l a relatively long passage to the other end of the l \"lintl(!'. a swingrint flap-valve hinged atone end in said ehainlier ha ving on opposite sides 01' the valve two valve-tacos for closing respertively said short direet passage and said relatively long passage, the said long passage l'fiillilllSlltL a substantial portion of the ap propriate tat-e, of the valve, and at least one throughwav aperture in the valve for adinitting driving-fluid to tl at side of the alve having the valve-'taee which closes said short direct passage to the cylinder but not to the said val ve-it'ace.

In testimony whereof we have signed our names to this specification.

JOHN LEONA RD HOLMAN. ARTHUR TREVE HOLMAN. 

